Bill in Co wrote:


It never even occurred to me that the depth of the gold plating was such a
controlled quantity in terms of those classes and the number of "rated
insertions". Or that the lightest coating was only intended to protect
against corrosion while in storage, and only while in storage, and nothing
more. Interesting.

In Telecom, it's 50 microns. A typical product life might be defined as "20 years".

In Computers, it's 10 microns. And presumably a shorter product life target.

One method of application is plate-up, which uses a series
of metals of appropriate metallurgy. Maybe copper followed
by nickel followed by gold. I've never been exposed to the design
details of such at work, so can't give a rationale for every
choice made there.

The other way of applying gold to something, is sputtering.
We had a sputtering setup in the Physics Department in university,
and the students used to make "gold sunglasses". The setup had
an interferometer, and you could count "wavelengths" as a measure
of the amount of gold applied. So instead of microns, it might
be some smaller number. I never made any sunglasses, so I
couldn't tell you how many wavelengths of visible light
were needed for a gold tinted sunglass lens. But the other
students got a kick out of this. Because they were making
Tom Cruise sunglasses.

In Telecom, one of the tests is "Corrosive Gas Mixtures",
where the equipment is exposed to hydrogen sulfide or
HCL gas or some other awful substance. Presumably some of those
connector design choices, are based on being able to pass
such tests. (This ensures that the most polluted urban
centers in the world, do not destroy telecom equipment.)

I couldn't tell you how Gold holds up to sliding contact
and repeated insertions - like what a typical number is for
matings. Versus say, tin on tin.

Tin on tin works by "biting" and making a gas-tight
metal to metal contact. It's not recommended to mix
the two metals (tin and gold), since they "work" by
different principles. You couldn't get the oxide off the
tin, if gold slid past it. It's gold on gold, or tin on tin,
or "get outta town".

Paul